1. Field of the Invention
This invention relates to a hydrazone compound which is useful as a photoconductive substance to be used in an electrophotographic photosensitive member.
2. Description of the Prior Art
Hydrazone compounds are known to be useful as photoconductive substances to be used in electrophotographic photosensitive members, and application thereof for electrophotographic photosensitive member and also processes for production thereof are disclosed in U.S. Pat. Nos. 4,150,987 and 4,278,747 as well as Japanese Laid-open patent application Nos. 52,064/1980, 81,552/1981 and 81,559/1981.
According to a process of the prior art, a hydrazone compound can be obtained by reducing a nitroso compound to be converted once to a hydrazine compound, which is then isolated and allowed to undergo condensation reaction with a carbonyl compound in a solvent. As the solvent, alcohols such as methanol, ethanol, etc and acetic acid are frequently used.
On the other hand, the aforesaid nitroso compound can be obtained by adding an aqueous solution of sodium nitrite dropwise into an aqueous solution of a hydrochloride of an amine compound. When carrying out the condensation reaction of a hydrazine compound obtained by reduction of this nitroso compound with a carbonyl compound, because this condensation reaction is a reaction which dislikes the presence of water, the hydrazine compound is once isolated and then allowed to undergo the condensation reaction with a carbonyl compound in the absence of water to synthesize a hydrazone compound.
However, most of hydrazine compounds are very unstable to be readily oxidized. When a hydrazine compound formed by reduction of a nitroso compound is once isolated, it is not possible in some cases to derive a hydrazone compound from the hydrazine compound, or the yield is considerably lowered. Moreover, it is difficult to carry out in the same solvent system the reactions ##STR2## whereby the production efficiency was worsened.
As the method known in the art for synthesizing a hydrazone in the same solvent system, in place of making sodium nitrite used during formation of a nitrosated product into an aqueous solution, anhydrous sodium nitrite powders are used and anhydrous acetic acid is used as the reaction solvent, and a carbonyl compound is added to the resultant liquid reaction mixture containing the nitrosated compound to carry out the condensation reaction.
This reaction, while it has the advantage of carrying out the reactions of amine.fwdarw.nitroso.fwdarw.hydrazine.fwdarw.hydrozone in the same solvent system, involves the drawbacks that nitrosation can difficultly be accomplished completely in the nitrosation reaction, and moreover that sodium nitrite not contributed to the reaction in the nitrosation step will remain in the reaction liquid system, which decomposes the hydrazine compound formed in the hydrazination step by reduction, thereby ultimately lowering markedly the synthesis yield of hydrazone.